Modern wind power plants customarily have a wind-powered rotor, the rotor blades of which are variable with regard to their angle of incidence (so-called pitch adjustment). To this end, drive devices are provided on the wind-powered rotor. As a rule, the drive devices are arranged in the rotor hub, wherein for reasons of power output and redundancy a separate drive device is associated with each rotor blade.
In general, drive devices, such as gearboxes and motors, require lubrication in order to forestall premature wear phenomena. The lubrication is usually carried out with oil. As a result of abrasion, the oil becomes contaminated and has to be changed regularly in the course of a maintenance. Thus, oil changes have to be carried out regularly even in the case of wind power plants. This requires the presence of a fitter in the engine nacelle of the wind power plant, which necessitates considerable expenditure especially in the case of a large number of wind power plants in a wind farm and/or in the case of wind power plants which are installed a distance away, for example in the case of offshore wind power plants.
A manual method for carrying out an oil change in the case of drive devices of wind power plants is described in the unexamined German application DE 10 2008 027 365 A1. According to this, in a first step the wind-powered rotor is rotated into a specified position (maintenance position) so that an oil sump of the drive device is located with its outlet opening at the bottom (relative to the drive device). The oil in the drive device is then over the outlet opening. By opening the outlet opening, the oil is drained and collected in a waste oil container. For filling with fresh oil, the wind-powered rotor is rotated by 180 degrees so that the outlet opening of the now emptied drive device is located at the top. The fresh oil is poured in and the outlet opening closed again. This process is repeated for each one of the other drive devices. Since the drive devices of such wind power plants are customarily arranged in the rotor hub with different orientation (specifically so that they have the same relative position in each case in relation to the rotor blade which is operated by it), the wind-powered rotor has to be further rotated each time in order to achieve the respective positions for emptying and filling. In the case of a wind power plant with a three-bladed wind-powered rotor, at least five rotations of the wind-powered rotor, starting from the maintenance position, have to consequently be carried out for an oil change of the drive devices. The high cost as a result of the repeated rotation of the wind-powered rotor, which requires a lot of time for one thing and a large number of personnel for another thing, is the disadvantage of this method.
From another field of technology, specifically the automobile industry, it is known to rapidly remove the oil and fill up with oil again through a single opening with the aid of a pump device. This device, however, is quite large and heavy and because of this is not suitable for portable use. It is therefore unsuitable for use during maintenance of wind power plants.